In conventional cotton pickers, for each row of cotton to be picked, there is provided a picker drum, which supports at least one vertical rotor assembly, which assembly consists of a plurality of radially extending, cotton-picking spindles. Each rotor, and its associated drive gears, are protected against damage by a slip clutch, which removes drive from the rotor when an overload occurs, e.g. when debris becomes lodged in the drum. That is, a rotor shaft extends downwardly through the slippable portion, or inner hub, at the center of the slip clutch, and then through the drum. The rotor drive gear is mounted to the external, driven portion, i.e. housing, of the slip clutch. As the slip clutch is driven by a conventional power source, via the drive gear, the rotor also rotates on its vertical axis, in tandem with the clutch.
During the overloaded condition, ratcheting or clicking sounds are generated as the cams and lobes on the drive and driven portions, of the gear train and clutch respectively, slip past each other. Absent a slippage detection system, an operator, seated in the cab of the cotton picker, must rely upon hearing the slipping sounds. However, he may not immediately hear the sounds because cabs tend to isolate the operator from the noise of the picker unit. This inability to immediately recognize the overload condition can result in damage to the drum and its drive, as well as reduced productivity from the loss of cotton.
Before now, the slippage detection systems measured the speed differential between the rotor assemblies of the picking drums. The drum rotor assembly normally comprises two rotor shafts per picking drum. Each rotor shaft of each drum, has a speed sensor, therefore there are 12 sensors on a 6 row machine. Each sensor measures the revolutions per minute (RPM) from its respective shaft and sends the signal to a computer processing unit that calculates the speed differential between the two shafts. A microprocessor captures the speed differential at each rotor assembly and the resulting average differential speed after comparing all six assemblies. The processor sends a fault warning if any rotor speed and/or speed differential deviates from the average by more than ±10%.
There are many factors influencing this fault warning. Typically, the shaft must spin a minimum number of RPMs before the computer processing unit can detect any degree of change. Most computer processors need a certain minimum number of cycles and time to process and validate signals from the speed sensor. Since damage continues to occur, during at least that minimum number of cycles, and during the processor cycle validation time, the delayed detection or late warning of the slippage leads to, inter alia, aggravation of the deterioration of various fine-tuned components of the harvester machines.
Identifying and repairing the damage to these fine-tuned components may exceed the troubleshooting capabilities of the average operator.